JP2006029224A - Exhaust device of engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust device of an engine with a supercharger which realizes an ultra-low back-pressurization of an exhaust system, reduction in air flow noise, and reduction in the capacity of a muffler. <P>SOLUTION: (1)The exhaust device 10 of the engine with the supercharger comprises a front muffler 12 and a rear muffler 13 which are mounted sequentially in the direction of an exhaust flow to an exhaust pipe connected with the engine with the supercharger. Each muffler of front and rear mufflers comprises an inner pipe 14 which continuously linearly extends from an exhaust inlet to an exhaust outlet and is not reduced in diameter in the middle of the interior of the muffler, and does not comprise an expansion chamber in the muffler.(2)A high-frequency resonance chamber 18 located outside the inner pipe 14 of the front and rear mufflers is hollow and does not have an inserted noise absorbing material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust system for a supercharged engine, and more particularly to a muffler structure.

The following two points are required for the exhaust system of a supercharged engine in terms of performance.
1) Ultra-low back pressure Engines with a supercharger tend to require a large amount of catalyst before the muffler due to a large displacement, and the engine back pressure tends to be high. In order to improve engine output, it is necessary to make the exhaust system have a very low back pressure.
2) Silence of high-frequency airflow sound In an engine with a supercharger, airflow sound (high-frequency sound) is generated due to a large displacement and high exhaust flow velocity, and as shown in FIGS. 1 (muffler having a high frequency resonance chamber, front muffler 1 in FIGS. 8 and 9) is required. For example, the muffler disclosed in Japanese Utility Model Laid-Open No. 6-25506 is a muffler having a high frequency resonance chamber. However, since the inner pipe is an inlet and is reduced in diameter with respect to the exhaust pipe, pressure loss occurs and supercharging is performed. The ultra-low back pressure required for the exhaust system of a mechanical engine cannot be realized.
Further, in order to reduce the air column resonance sound (low frequency sound) generated by the length of the exhaust pipe at the time of deceleration, or to mute the propagation sound, the main muffler 2 (which has an expansion chamber 3 and has a discontinuous pipe) ( The rear muffler 2) shown in FIGS. 8 and 9 is installed. In the main muffler 2 having an expansion chamber, an air flow sound (high frequency sound) is generated due to the turbulence of the air flow in the muffler, particularly at the pipe entrance, and the high frequency sound is silenced in the main muffler or downstream of the main muffler. A reduction muffler 4 is provided.
Japanese Utility Model Publication No. 6-25506

For the rear main muffler, a muffler having an expansion chamber having the same structure and size as that for the exhaust system of a supercharger-less engine is used for common parts. Therefore, there are the following problems.
B) Extremely low back pressure is difficult In the rear main muffler with an expansion chamber, the flow of exhaust turns and the flow path expands and contracts, so the pressure loss increases and it is difficult to reduce the back pressure.
B) Airflow sound (high-frequency sound) is generated Airflow sound (high-frequency sound) is generated in the rear main muffler of the expansion room type. In particular, the flow is disturbed at the pipe inlet in the muffler and airflow noise is generated. In order to mute the noise, a special muffler for reducing high frequency sound is provided in the main muffler, which increases the size of the muffler and the complexity of the structure.
C) Large muffler capacity and low muffler silencing efficiency In an engine with a supercharger, exhaust energy is taken at the turbine site, and the engine explosion order component (low frequency sound) should hardly be transmitted downstream, but an engine without a supercharger The engine explosion order sound is reduced to the same extent as the, and the muffler capacity is unnecessarily large. This means that the muffler silencing efficiency per unit capacity is poor.

  An object of the present invention is to provide an exhaust system for an engine with a supercharger capable of realizing an ultra-low back pressure in an exhaust system, reducing airflow noise, and reducing a muffler capacity.

The present invention for solving the above problems and achieving the above object is as follows.
(1) The exhaust pipe connected to the supercharged engine is provided with a front muffler (in the present invention, the front muffler is the main muffler) and a rear muffler (in the present invention, the rear muffler is the sub muffler) in the exhaust flow direction. An exhaust system for an engine with a supercharger, wherein each of the front muffler and the rear muffler has an inner pipe that continuously extends linearly from the exhaust inlet of the muffler to the exhaust outlet and is not reduced in diameter in the middle of the muffler. An exhaust system for an engine with a supercharger that is provided and does not have an expansion chamber in the muffler.
(2) The supercharged engine according to (1), wherein the front muffler has a high frequency resonance chamber outside the inner pipe, and the rear muffler has a low frequency resonance chamber and a high frequency resonance chamber outside the inner pipe. Exhaust system.
(3) The low frequency resonance chamber and the high frequency resonance chamber outside the inner pipe of the rear muffler are provided in the order of the low frequency resonance chamber and the high frequency resonance chamber in the exhaust flow direction. Exhaust system.
(4) The supercharged engine according to (2), wherein the inner pipes of the front muffler and the rear muffler have a louver hole that communicates the inside of the inner pipe and the outer high frequency resonance chamber in a portion where the high frequency resonance chamber is located outside. Exhaust system.
(5) The exhaust system for a supercharged engine according to (2), wherein a high-frequency resonance chamber outside the inner pipes of the front muffler and the rear muffler is a space and no sound absorbing material is inserted.

According to the exhaust system for an engine with a supercharger (1), the inner pipe extends linearly and is not reduced in diameter in the middle of the muffler, so that the pressure loss is small and the exhaust system has an ultra-low back pressure. . This significantly improves the output of the supercharged engine.
Since there is no expansion chamber in the muffler, there is no turbulence in the flow from the expansion chamber to the pipe in the muffler, and airflow noise can be reduced.
Since there is no expansion chamber, the capacity of the muffler can be reduced by setting the low frequency resonance chamber to the minimum necessary capacity.
According to the exhaust system for an engine with a supercharger (2), the front muffler has a high frequency resonance chamber outside the inner pipe, and the rear muffler has a low frequency resonance chamber and a high frequency resonance chamber outside the inner pipe. Therefore, it is possible to reduce airflow noise and sound due to air column resonance during deceleration.
According to the engine exhaust system with a supercharger of (3) above, the low frequency resonance chamber and the high frequency resonance chamber outside the inner pipe of the rear muffler are provided in the order of the low frequency resonance chamber and the high frequency resonance chamber in the exhaust flow direction. As a result, airflow noise coming out from the rear end of the exhaust pipe can be suppressed.
According to the exhaust system for an engine with a supercharger of (4) above, the inner pipe has a louver hole that communicates the inside of the inner pipe with the outer high frequency resonance chamber, so that a sound absorbing material such as glass wool is provided in the high frequency resonance chamber. Even if there is no sound, the sound absorption effect is almost the same as when there is a sound absorbing material through the louver hole.
According to the exhaust device for an engine with a supercharger (5), the sound absorbing material can be prevented from being scattered by eliminating the sound absorbing material.

Hereinafter, an exhaust device for a supercharged engine according to the present invention will be described with reference to FIGS.
An exhaust device 10 for a supercharged engine according to the present invention includes an exhaust pipe 11 connected to the supercharged engine, and a muffler 12 provided in the exhaust pipe 11. The muffler 12 includes at least one of a front muffler (main muffler) 12 and a rear muffler (sub muffler) 13 provided in order in the exhaust flow direction in the exhaust pipe 11 (only the rear muffler may be used). When both the front muffler 12 and the rear muffler 13 are provided, the front muffler 12 and the rear muffler 13 may be provided separately as shown in FIG. 1, or the front muffler 12 and the rear muffler 13 may be integrated.

  The supercharged engine of FIG. 1 is, for example, a V-type 8-cylinder or 6-cylinder diesel or gasoline engine having both left and right banks, and has a turbocharger turbine in the exhaust pipe from each bank. It has a diesel particulate removal device and a catalytic converter (may be only a catalytic converter) downstream, a front muffler 12 downstream thereof, and the exhaust pipes from the left and right banks are gathered into one exhaust pipe downstream thereof, A rear muffler 13 is provided downstream thereof. However, the engine is not limited to the V type but may be an in-line engine, the number of cylinders is not limited to 8 or 6 cylinders, and may be 12 cylinders, 4 cylinders, and the like, and the exhaust pipe configuration is also turbine, front muffler Are not limited to those provided upstream of the collecting portion, but may be provided in one exhaust pipe downstream of the collecting portion or one exhaust pipe of an in-line multi-cylinder.

As shown in FIGS. 2 and 3, each of the muffler of the front muffler 12 and the rear muffler 13 includes an inner pipe 14 and an outer casing 15 outside the inner pipe 14.
The inner pipe 14 continuously extends in a straight line from the exhaust inlet 16 to the exhaust outlet 17 of the muffler. The inner pipe 14 is not reduced in diameter in the middle of the muffler (in order to suppress pressure loss, diameter expansion is allowed, but diameter reduction is not allowed), and the current plate extends in the direction of blocking the flow in the inner pipe 14. Does not have.
Further, each of the muffler of the front muffler 12 and the rear muffler 13 does not have a conventional expansion chamber in the muffler.

A space between the inner pipe 14 and the outer casing 15 outside the inner pipe 14 constitutes a resonance chamber.
The front muffler 12 has a high frequency resonance chamber 18 outside the inner pipe 14 (there is no low frequency resonance chamber), and the rear muffler 13 has a low frequency resonance chamber 19 and a high frequency resonance chamber 18 outside the inner pipe 14. ing.
The low frequency resonance chamber 19 and the high frequency resonance chamber 18 outside the inner pipe 14 of the rear muffler 13 are provided in the order of the low frequency resonance chamber 19 and the high frequency resonance chamber 18 in the exhaust flow direction.

  The high-frequency resonance chamber 18 silences the exhaust airflow sound (high-frequency sound of 1 kHz or more, “sharsh”) in the engine with a supercharger whose displacement is large, and the low-frequency resonance chamber 19 is an engine with a supercharger. The sound of the engine explosion order component without a supercharger (ie, a low-frequency sound lower than 1 kHz, for example, 150 to 200 Hz and a “buzz” sound) is muted.

  The inner pipe 14 of the front muffler 12 and the rear muffler 13 has a plurality of louver holes 20 that communicate the inside of the inner pipe 14 and the outer high frequency resonance chamber 18 at a portion where the high frequency resonance chamber 18 is located outside. The louver hole 20 is cut and raised outward in the radial direction of the inner pipe 14. The louver hole 20 is manufactured by putting a slit in a flat plate or pipe and applying a tensile force in a direction orthogonal to the slit, and has a hole shape other than circular.

The inside of the high frequency resonance chamber 18 outside the inner pipe 14 of the front muffler 12 and the rear muffler 13 is a space, and no sound absorbing material (glass wool or the like) is inserted therein.
The low frequency resonance chamber 19 and the high frequency resonance chamber 18 outside the inner pipe 14 of the rear muffler 13 are blocked by a partition plate 21.
The low frequency resonance chamber 19 outside the inner pipe 14 of the rear muffler 13 is composed of an air column constituting space between the skirt 22 attached to the inner pipe 14 and the inner pipe 14. One end of the air column structure space is opened between the inner pipe 14 and the outer casing 15, and the other end of the air column structure space is closed, and the exhaust in the inner pipe 14 is formed by the communication opening 23 formed in the inner pipe 14. It communicates with the gas flow path. The communication opening 23 may be a round hole or a slit extending in the circumferential direction of the inner pipe 14.

In the conventional exhaust system, the expansion chamber type rear muffler has a larger capacity than the front muffler, the rear muffler is the main muffler, and the front muffler is the sub muffler.
On the other hand, in the present invention, as shown in FIG. 4, the rear muffler 13 does not have an expansion chamber and is miniaturized. Therefore, the rear muffler 13 has a smaller capacity than each front muffler 12, and the front muffler 12 is a main muffler. The rear muffler 13 is a sub muffler. For example, in the present invention, the front muffler 12 has 9.3 L × 2 units, and the rear muffler 13 has 7.5 L × 1 units. However, L is 1000 cm ³ in liters.

Further, when the back pressure in the V-type 8-cylinder diesel was examined, the engine back pressure exceeded 50 kPa in the conventional exhaust system for a supercharged engine, but the exhaust system for a supercharged engine of the present invention. 10 is an exhaust system in which a diesel particulate purification device (DPNR), an oxidation catalyst device (20R), a main muffler 12 (M / M), and a sub muffler 13 (S / M) are arranged in this order. Compared with that, the pressure decreased by about 8 kPa, resulting in an ultra-low back pressure.
In addition, the pressure loss of the main muffler (front muffler without the expansion chamber) in the exhaust device 10 of the present invention is reduced by about 5 kPa compared to the pressure loss of the conventional main muffler (rear muffler having the expansion chamber). However, the pressure loss in the DPNR catalyst and the pressure loss in the oxidation catalyst (20R catalyst) are the same in the conventional and the present invention.

5 to 7 show the results of the exhaust sound evaluation test performed in a plurality of cases A, B, and C with different specifications. The engine used was a V-type 8-cylinder diesel engine with an intake air amount of 296 g / S, an output of 210 kW, and a torque of 660 Nm.
As shown in FIG.
In case A, there is a sub muffler (rear muffler 13), and the inner pipe diameter in the sub muffler is 61 mm.
Case B has no sub-muffler (rear muffler 13) and the pipe diameter is 70 mm.
Case C has no sub-muffler (rear muffler 13) and the pipe diameter is 60.5 mm.

As shown in FIG. 6, in acceleration, the effect of exhaust noise reduction is higher in case A (with sub-muffler, pipe diameter 61 mm) than in case C (no sub-muffler, pipe diameter 60.5 mm). In the case of B (no sub-muffler, pipe diameter is 70 mm), the exhaust noise reduction effect is higher than when the sub-muffler is provided and the pipe diameter is 61 mm. From now on, in acceleration, airflow noise is the main, with sub-muffler is better than without sub-muffler, and by increasing the pipe diameter (by not reducing the pipe diameter), the exhaust noise reduction effect can be drastically reduced. It turns out that it becomes high.
As shown in FIG. 6, in deceleration, the effect of reducing the engine explosion order component is higher in case A (with sub-muffler and pipe diameter 61 mm) than in case B (no sub-muffler, pipe diameter 70 mm). From this, it can be seen that, in deceleration, providing a sub-muffler (rear muffler 13) is effective in reducing exhaust noise.

FIG. 7 shows the result of frequency analysis in FIG. 6 at a full load of 4000 rpm and no load.
From FIG. 7, in the high frequency region (air flow sound region) with a frequency of 1 kHz or more, the exhaust sound is more in the case A (with the sub muffler and the pipe diameter 61 mm) than in the case C (no sub muffler, pipe diameter 60.5 mm). The reduction effect is high, and the exhaust noise reduction effect is higher in the case B (no sub-muffler, pipe diameter 70 mm) than in the case A (with sub-muffler, pipe diameter 61 mm). From this, it can be seen that in acceleration, airflow noise is the main effect, and by increasing the pipe diameter (by not reducing the pipe diameter), the exhaust noise reduction effect increases rapidly.

Next, functions and effects of the present invention will be described.
In the exhaust device 10 for a supercharged engine according to the present invention, the inner pipe 14 extends linearly and is not reduced in diameter in the middle of the mufflers 12 and 13 (it is not reduced in diameter compared to the exhaust pipe). The pressure loss at the mufflers 12 and 13 is small, and the exhaust system has an extremely low back pressure (target 50 kPa or less). This significantly improves the output of the supercharged engine. The turbocharged engine recovers exhaust energy with a turbine and turns the compressor to supercharge it. Therefore, the output is large and the displacement is large, but the conventional expansion main muffler is used as the exhaust system. If it is provided, the pressure loss at the main muffler becomes too large and the large output, which is the goodness of the supercharged engine, cannot be drawn. However, by using the exhaust device 10 of the present invention, the pressure loss at the mufflers 12 and 13 is reduced. It becomes smaller, the exhaust system becomes super low back pressure, and the output of the engine with the supercharger is remarkably improved.

  Since there is no expansion chamber in the mufflers 12 and 13, there is no turbulence in the flow from the expansion chamber existing in the conventional expansion chamber type muffler to the pipe in the muffler, which occurs when the conventional expansion chamber type muffler is used. The airflow noise that had been reduced can be reduced. In the case of using a conventional expansion chamber type muffler, a high-frequency sound reduction muffler provided with a large sound-absorbing material is provided downstream of the expansion chamber in order to reduce airflow noise. As well as the high-frequency resonance chamber 18 of the rear muffler 13.

  Further, since there is no expansion chamber in the mufflers 12 and 13, the muffler capacity can be reduced by setting the low frequency resonance chamber 19 to the minimum capacity. Conventionally, in an engine with a supercharger, the sound of the engine explosion order component (low-frequency sound) hardly passes through the turbine to the exhaust pipe end, so it is not necessary to provide a large-capacity low-frequency resonance chamber. First, by sharing parts, an expansion chamber type muffler was used to provide an unnecessarily large capacity low frequency resonance chamber. However, in the present invention, the low frequency resonance chamber 19 in the rear muffler 13 is minimized. By setting the capacity, the muffler capacity can be reduced. This improves the mountability on the vehicle.

Since the front muffler 12 has a high-frequency resonance chamber 18 outside the inner pipe 14, and the rear muffler 13 has a low-frequency resonance chamber 19 and a high-frequency resonance chamber 18 outside the inner pipe 14, high-frequency sound during acceleration, etc. (Airflow sound) and low frequency sound during deceleration can be reduced.
Since the low-frequency resonance chamber 19 and the high-frequency resonance chamber 18 outside the inner pipe 14 of the rear muffler 13 are provided in the order of the low-frequency resonance chamber 19 and the high-frequency resonance chamber 18 in the exhaust flow direction, they exit from the rear end of the exhaust pipe. The coming airflow sound can be effectively suppressed.

Since the inner pipe 14 has a louver hole 20 that communicates the inside of the inner pipe and the outer high frequency resonance chamber 18, even if the high frequency resonance chamber 18 does not have a sound absorbing material such as glass wool, the sound absorbing material is provided by the louver hole 20. A sound absorption effect almost equal to that of the case can be obtained.
Further, by eliminating the sound absorbing material, it is possible to eliminate the scattering of the sound absorbing material and the deterioration of the sound absorbing characteristics due to the scattering.

1 is a system diagram of an exhaust device for a supercharged engine according to the present invention. It is a schematic block diagram of the front muffler of the exhaust apparatus of the engine with a supercharger of this invention. It is a schematic block diagram of the rear muffler of the exhaust apparatus of the engine with a supercharger of this invention. It is a top view of the exhaust device of the engine with a supercharger of the present invention. It is a schematic block diagram of a plurality of cases A, B, and C with different specifications. 6 is a graph of sound pressure level / engine speed in the exhaust sound test of A, B, and C in the case of FIG. 5. It is a graph of the sound pressure level / frequency of the data taken out at a rotational speed of 4000 rpm in FIG. It is a systematic diagram of the exhaust system of the conventional supercharged engine. It is a schematic block diagram of the front muffler of the exhaust apparatus of the conventional supercharged engine. It is a schematic block diagram of the rear muffler of the exhaust apparatus of the conventional supercharged engine.

Explanation of symbols

10 Exhaust System for Engine with Supercharger 11 Exhaust Pipe 12 Front Muffler (Main Muffler)
13 Rear muffler (sub muffler)
14 Inner pipe 15 Outer casing 16 Muffler exhaust inlet 17 Muffler exhaust outlet 18 High frequency resonance chamber 19 Low frequency resonance chamber 20 Louver hole 21 Partition plate 22 Skirt 23 Opening for communication

Claims (5)

  An exhaust system for a supercharged engine having a front muffler and a rear muffler in order in an exhaust flow direction in an exhaust pipe connected to the engine with a supercharger, wherein each muffler of the front muffler and the rear muffler is an exhaust inlet of the muffler An exhaust system for an engine with a supercharger that includes an inner pipe that continuously extends in a straight line from the exhaust outlet to the exhaust outlet and is not reduced in diameter in the middle of the muffler and does not have an expansion chamber in the muffler.   The exhaust system for a supercharged engine according to claim 1, wherein the front muffler has a high frequency resonance chamber outside the inner pipe, and the rear muffler has a low frequency resonance chamber and a high frequency resonance chamber outside the inner pipe. .   The exhaust system for an engine with a supercharger according to claim 2, wherein the low frequency resonance chamber and the high frequency resonance chamber outside the inner pipe of the rear muffler are provided in the exhaust flow direction in the order of the low frequency resonance chamber and the high frequency resonance chamber.   The exhaust system for an engine with a supercharger according to claim 2, wherein the inner pipe of the front muffler and the rear muffler has a louver hole that communicates the inside of the inner pipe and the outer high frequency resonance chamber at a portion where the high frequency resonance chamber is located outside. .   The exhaust system for an engine with a supercharger according to claim 2, wherein a high-frequency resonance chamber outside the inner pipes of the front muffler and the rear muffler is a space and no sound absorbing material is inserted.

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